April 23, 2008

Security advisory

= SugarCRM Community Edition Local File Disclosure Vulnerability
= Vendor Website:
= http://www.sugarcrm.com
= Affected Version:
= -- SugarCRM Community Edition 4.5.1
= -- SugarCRM Community Edition 5.0.0
= Public disclosure on 23rd April 2008
Available online at:
http://www.security-assessment.com/files/advisories/2008-04-29_SugarCRM_ local_file_disclosure.pdf

== Overview ==
SugarCRM Community Edition is vulnerable to local file contents disclosure.
This vulnerability can be exploited by a malicious user to disclose potentially sensitive information. The flaw is caused due to a lack of input filtering in the SugarCRM RSS module, which can be exploited
to disclose the content of local files.

The RSS module allows SugarCRM users to add RSS feeds to their personal RSS list. The application expects an URL value pointing to a valid RSS feed.
However, the URL variable value is not properly sanitised and any URI value can be entered instead. In this particular case, it was discovered that it is possible to enter a file path to any files on the local system hosting the SugarCRM application.

As a result SugarCRM does not display the new RSS feed in the list as it is not a valid RSS URL Feed. However, the application creates a local file with the filename of the md5 hash of the URL entered. The file is created in the directory cache/feeds . If the Apache web server is used, the file is created with the user www-data containing read permission.

== Exploitation ==

An exploitation example in a LAMP (Linux, Apache, Mysql, PHP)

If an authenticated attacker enters a value of “/etc/passwd”
(without quotes) in the RSS URL field, the application will generate a MD5 hash of the string containing the file path. In this case,
the value “/etc/passwd” is hashed to “c5068b7c2b1707f8939b283a2758a691
” (without quotes). The MD5 hash is then used as a filename with the file contents of /etc/passwd. The file /etc/passwd can then be viewable
publicly at http://sugarwebsiteaddress/cache/feeds/c5068b7c2b1707f8939b2
83a2758a691 .

Exploitation of this flaw does not require authentication.

The URL variable is handled by the /modules/Feeds/Feed.php page.
The array variable $url is passed without filtering to the
xml_domit_rss_document function at the following line:

$rssdoc = new xml_domit_rss_document ($this->url, ‘cache/feeds/’, 3600);

The XML domit RSS plugin is then called and retrieves the file content at the path given and then generate the MD5 hashed file in the cache/feeds folder as instructed by the function in Feed.php .

== Solutions ==

Install the vendor supplied patches.
Patch 4.5.1j: http://www.sugarcrm.com/forums/showthread.php?t=31688
Patch 5.0.0c: http://www.sugarcrm.com/forums/showthread.php?t=32252

== Credit ==

Discovered and advised to SugarCRM
April 2008 by Roberto Suggi Liverani of Security-Assessment.com

== Greetings ==

To all my SA colleagues and thanks to the great atmosphere in
Hack in the Bush!
It was inspirational...

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